Defrost system for refrigerated cabinets



April 21, 1959 B. l.. HERRMANN ETAL 2,882,696

DEFRosT ASYSTEM FOR REFRIGERATED cABINETs Filed June 4. 1956 4 Sheets-Sheet 1 ppit'a/c 4? 9,30

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DEFRosT SYSTEM FOR REFRIGERATED cABINETs lFiled June 4, 1956 4 sheets-sheet 2 /V M, wlw, www@ April 21, 1959 B. l.. HERRMANN ET AL 2,882,695

DEFRosT SYSTEM FOR REFRIGERATED CABINETS Filed June 4, 1956 4 Sheets-Sheet 3 pray/nays,

April 21, 1959 B'. L. HERRMANN ET AL 2,882,696

DEFROST SYSTEM FOR REFRIGERATED CABINETS ef/MPVL lm/MAW fa-rez Efe/Fass y @wwf w@ United States Patent @ihre 2,882,696 Patented Apr. 21, 1959 DEFROST SYSTEM FOR REFRIGERATED CABINETS Bernard L. Herrmann, Aiton, and Lester F. Reifeiss, House Springs, Mo., assignors to Anheuser-Busch, In-

corporated, St. Louis, Mo., a corporation of Missouri Application June 4, 1956, Serial No. 589,143

Claims. (Cl. 62-155) This invention relates in general to a defrost system for refrigerated cabinets and in particular to a defrost system for refrigerated cabinets having an upper cooling coil and a food compartment cooling coil wherein the upper cooling coil can be defrosted by relatively hot refrigerant which is then used to cool the food kcompartment.

The use of refrigerated cabinets in commercial establishments is becoming more common, especially in supermarkets, drug stores and the like which use open top or reach-in refrigerated display cabinets. In general, such cabinets have been refrigerated by means of one or more evaporators or coils with forced or convectional air currents over them and the product, or by means of i evaporators in contact with the product, or a combination thereof. In the past, it has been common to defrost all or part of the evaporator or evaporators, with the result that the contents within the food compartment were not held at a constant low temperature but were subjected to periodic temperature rises during defrosting. The temperature rise was due to room air entering the open top of the cabinet, heat leakage through the coils and from the defrosting means themselves. In some past installations, the evaporators were defrosted by separate heating means positioned in contact with or near passes of the evaporators or coil. These heating means were either electrical heaters or resistance wires. In some cases, they comprised separate parallel conduits which carried hotrefrigerant to defrost said coils. When hot refrigerant was used to defrost in the past, the refrigerant was redirected to a re-evaporator and back to the compressor so that little or not refrigeration took place within the refrigerated compartment.

One of the principal objects of the present invention is to defrost the upper coil of a refrigerated cabinet by obtaining heat for said defrost from the product Within the food compartment.

Another object of the present invention is to use the refrigerant to rst defrost the upper coil and then direct said refrigerant into the tank coil to cool the tank or food compartment so that the upper coil or evaporator is being defrosted While the tank coil or evaporator is chilling the food compartment.

Another object is to provide a defrost system wherein hot refrigerant is transmitted directly to a defrost coil which is positioned parallel to the upper coil thereby melting the frost thereon, and is then directed through a capillarytube and into the tank coil circumscribing the food compartment where the refrigerant then chills the food compartment.

Another object is to direct hot refrigerant which has defrosted the upper coils through a restrictor or capillary tube and into the tank coil so that the single circuit having refrigerant therein defrosts the upper coil and chills the food compartment atthe same time.

These and other objects and advantages will become apparent hereinafter.

The invention also consists in the parts and in the ar- 2 rangements and combinations of parts hereinafter described and claimed. In the accompanying drawings which form part of this specification and wherein like numerals and symbols refer to like parts wherever they occur:

Fig. 1 is a diagrammatic illustration of a typical system embodying the present invention, said system shown in its normal or refrigerating cycle, the defrost means being shown in dotted lines,

Fig. 2 is a diagrammatic illustration of the system shown in Fig. l during the defrost cycle,

Fig. 3 is a perspective view of a refrigerated cabinet embodying the defrost system and defrost means of this invention, the outer walls of said cabinet removed for clarity,

Fig. 4 is a cross-sectional view of a refrigerated cabinet embodying the present invention taken slightly inwardly of the end wall,

Fig. 5 is a diagrammatic illustration of a modified system embodying the present invention, said system shown in its normal or refrigerating cycle,

Fig. 6 is a diagrammatic illustration of the system shown in Fig. 5 during the defrost cycle, and

Fig. 7 is a cross-sectional View of a cabinet using the modified system taken slightly inwardly of the end wall.

Referring now to the drawings in detail, it will be seen that the embodiment of the invention which has been illustrated is shown in a refrigerated cabinet 1 having a food compartment 2 circumscribed by a tank coil or evaporator 3 and an upper coil or evaporator 4 positioned thereabove at the rear portion of said cabinet 1.

The refrigerated cabinet 1 comprises two end walls 5, a front wall 6, and a relatively higher rear wall 7 having a superstructure 8 forwardly thereof which covers the upper evaporator 4 which has several passes 9 therein. The cabinet 1 is provided with a relatively large food compartment 2 which is preferably made of metal and surrounded immediately by a tank evaporator 3 having a plurality of coils or passes 10 therein positioned one above the other.

Except at night, the food compartment is completely open at the top to provide ready access for customers who might want to reach into the food compartment to select a certain item. In order to maintain each of the many articles in the food compartment 2 at a constant desired temperature, a ow of cold air is directed over the top level of the food compartment 2 as indicated by the arrows 11. Because of this constant circulation of cold air, moist air from the surrounding room spills into the large reach-in opening 12, mixes with the cold circulating air and is eventually circulated over the upper evaporator 4 where some of its moisture is deposited on the individual coils or passes 9 thereof. It therefore becomes necessary to defrost said upper coil 9 periodically and far more frequently than the tank coil 3.

The bottom compartment 13 contains the refrigerating apparatus including a compressor 14, a condenser 15, a fan 16, and a two-way control valve 17 actuated by a solenoid 18. The condenser 15 has a refrigeration restriction or restrictor 19 extending therefrom which leads to a conduit 20 extending to the top pass 21 of the tank evaporator 3, which is provided with several intermediate passes 22 positioned below said top pass 21, and a bottom pass 23 which is attached to a conduit 24 which extends upwardly to one end of the upper coil 4, the opposite end of which leads to a downwardly extending conduit 25 which leads to the lower end of an inclined accumulator 26 having a conduit 27 extending therefrom to the compressor 14.

The accumulator 26 provides a reservoir for refrigerant to insure the proper amount of refrigerant within the system rat all times regardless of the temperature of the sur rounding room. The accumulator 26, which is tilted slightly upwardly from horizontal, also prevents liquid refrigerant from entering and damaging the compressor.

The defrost system 28 best shown in Figs. 2 and 3 includes the two-way valve 17, an upwardly extending bypass -or defrost line 29 which leads to a drain pan, which collects defrost water from the upper coil, and then to an upper defrost coil which is positioned adjacent to and parallel to the individual passes 9 of the upper coil 4. A drain line is soldered to the defrost line 29 and directs the defrost water from the drain pan to the bottom compartment for evaporation. The drain line is the first in the series to be defrosted. The defrost coil 39 has several individual passes or turns 31a which are positioned immediately above said drain pan, as best shown in Fig. 3, and other passes 31 which are positioned parallel to and adjacent to the individual passes 9 of the upper evaporator 4. A downwardly extending conduit 32 eX- tends from the end of the upper defrost coil 31! to a vertically positioned receiver or accumulator 33 having aline extending therefrom to a defrost restrictor 34 which is connected to the upper pass 21 of the tank coil or evaporator 3. A shunt conduit is positioned between an intermediate pass 22 and the Iaccumulator 26 thereby bypassing the bottom pass 23. A two-way defrost valve 36 actuated by a solenoid 37 is mounted in the shunt conduit 35. Temperature control means 38 and a clock mechanism 39 are operatively connected to the compressor for controlling the valves to place the cabinet either in its normal cycle, as best shown in Fig. l, or in its defrost cycle, as best shown in Figs. 2 and 3` The temperature control means 38 causes the compressor 14 to operate at a certain predetermined low temperature in the food compartment 2 and shuts olf the compressor 14 when the temperature in the food compartment 2 has been reduced to a predetermined value. The defrost cycle is actuated by the clock mechanism 39 which periodically, for example every eight hours, actuates the solenoids 18 and 37 and the valves 17 and 36 to defrost the upper evaporator 4.

During normal refrigeration, shown in Fig, 1, the compressor 14 compresses a gaseous refrigerant and forces it through the pressure line into the condenser 15 which dissipates the heat generated by compression of the gas and the latent heat of vaporization. The refrigerant is then directed through the refrigeration restrictor 19 and then upwardly into the top pass 21 of the tank coil 3 where it then flows `.around the food compartment 2 spirally downwardly through the intermediate passes 22 to the bottom coil 23 thereof and then upwardly through the conduit 24 to and through the upper coil 4, then downwardly through the conduit 25 to the accumulator 26 and then back through the conduit 27 to the compressor 14. The cycle is continued until the desired temperature within the food compartment 2 is reached, at which time the temperature control 38 prevents further refrigeration until the temperature has raised a predetermined amount. The refrigerant in the tank coil 3 takes heat from the food compartment 2, thereby chilling the contents. Similarly, the upper coil 4 takes heat from the air which is directed over the exposed top portion of the food compartment 2 to chill .the top horizontal level of articlestherein.

The defrost cycle is controlled by the two-way control valves 17 and 36 which in turn may be controlled manually or with a clock or timing mechanism 39 so that the upper coil 4 will be defrosted periodically. During the defrost cycle, shown in Figs. 2 and 3, hot refrigerant is directed upwardly through Ythe by-pass or conduit 29 directly to the drain pan and upper defrost coil 30 and then through the individual turns 31 thereof which run parallel to the frost coated passes 9 of the upper coil 3 which is to be defrosted. Heat is given up by the hot refrigerant in defrosting the upper coil 4 with the result that the refrigerant liqueies. The liquid refrigerant is then directed downwardly through the conduit 32 into the receiver 33 and defrost restrictor 34 which expands the refrigerant as it passes therethrough and enters the top turn 21 of the tank coil 3. In its expanded state, the refrigerant again acts as a cooling medium for chilling the contents of the food compartment 2 just as in the normal cycle. Thus, the hot refrigerant rst defrosts the upper coil 4 and is then expanded and directed into the upper turn of the tank coil 3 where it cools the food compartment 2 and flows spirally downwardly in said tank coil 3 to a lower two-Way valve 36 in the shunt conduit 35 which directs it into the accumulator 26 and then back to the compressor 14. The shunt conduit 35 is placed between an intermediate pass 22 and the accumulator 26 thereby by-passing the bottom pass 23 so that the refrigerant cannot enter the vertical conduit 24 and be redirected into the upper evaporator 4.

The advantage of this defrost system in that the food, ice cream, or other items in the food compartment are maintained at a low constant temperature regardless of whether the upper evaporator 4 is cooling the surrounding air or is being defrosted. In both cycles, refrigerant enters the top pass 21 of the tank coil 3 moves spirally downwardly therearound and enters the accumulator 26. This is accomplished by means of the two solenoid actuated valves 17 and 36 and a connection immediately adjacent to the defrost restrictor 34 which prevents upward ow therethrough automatically and only allows relatively hot refrigerant to expand therethrough. The movement of the refrigerant to said tank coil 3 is best shown inFg. 2. Thus, the contents in the food compartment 2 remain at a stable low temperature and are used as a heat reservoir. During the defrost cycle, the tank coil 3 yoperates ata lowertemperature than normal and tends to lower the temperatures of portions of the product somewhat.

A modified form of the invention is shown in Figs. 5-7. 'I'his modified defrost system is used in the identical refrigerated cabinet as the form of the invention hereinbefore described. The refrigeration and defrost systems are substantially identical except that in the modified form the shunt conduit 35 and the valve 36 therein are eliminated. This is accomplished by directing the refrigerant first to the upper evaporator 4 and then into the tank evaporator 3 during the refrigeration cycle, as shown in Fig. 5, rather than directing the refrigerant first into the tank evaporator 3 and then into the upper evaporator 4 as shown in Fig. l.

In the modied form, a defrost restrictor 41 is provided between the upper evaporator 4 and the tank evaporator 3. The defrost restrictor 41 may be physically located within the superstructure housing the upper evaporator 4, as shown in Fig. 7, or as in the principal form may be located below the upper evaporator 4 adjacent to the tank evaporator 3. During normal refrigeration in the modified system shown in Fig. 5, the gaseous refrigerant passes from the compressor 14 through the pressure line 40 to the condenser 15 and then through the refrigeration restrictor 19 to an upwardly extending conduit line 20 into the upper evaporator 4 yand then into the tank evaporator 3 where it flows spirally downwardly through the individual passes 21, 22, and 23 thereof into an accumulator 26 and then back through the conduit 27 to the compressor I4. During the defrost cycle as best shown in Fig. 6, hot refrigerant is directed into an upwardly extending by-pass line 29 controlled by the three-way valve 42 therein and into the defrost -coil 30 whose individual passes 31 are mounted parallel to and adjacent to the individual passes 9 of the upper evaporator 4. The hot refrigerant after defrosting the upper evaporator 4 is then directed into .a defrost restrictor 41 and then into the top pass 21 of the tank evaporator 3 to the accumulator 26 and then back to the compressor 14.

In the modified form, the shunt conduit 35 and one valve 36 are eliminated but a three-way valve 42 must be substituted for the two-way valve 17 in the principal form.

5. n most refrigerated cabinet constructions vwherein the refrigeration apparatus including the condenser and the compressor are located at the bottom of the cabinet adjacent to the tioor, the air intake is positioned opposite to said apparatus in the lower portion, usually in a lower corner, of the cabinet. The present refrigerated cabinet may be provided with a separate front panel 43 which forms the front wall 6 of the cabinet. The front panel 43 is provided with an upper flange 44 for securing it to the cabinet, an outwardly inclined perforated upper portion 45 having holes 46 therein, an inwardly extending lower portion 47 having a bottom 48 and lower se-l curing ange 49. The front panel 43 extends horizontally across the entire front wall of the cabinet in spaced relationship from the insulation surrounding the food compartment 2. The holes 46 in the upper inclined portion 45 form an elevated .air intake for the compressor 14 and condenser 15 and the inwardly inclined lower portion 47 forms a downwardly extending space or duct 50 which together with the small substantially horizontal bottom 48 directs air into said refrigeration apparatus. If desired, baffles may be placed vertically and angularly Within the space 50 to direct air entering the holes 46 near the end walls of the cabinet 1 directly to the refrigeration apparatus. This elevated air intake construction might be the subject matter of a separate application which might be tiled by at least one of the inventors herein.

This invention is intended to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

What we claim is:

1. A refrigeration system including a compressor, a condenser, and a refrigeration restriction operatively connected for circulating refrigerant, .an upper evaporator and a tank evaporator each having several coils for receiving refrigerant, the coils of said tank evaporator arranged one above the other .along the wall of a tank or food compartment, the coils of lsaid upper evaporator positioned above the level of said food compartment, an accumulator mounted between said tank evaporator and said compressor, a by-pass line extending from said compressor to a defrost coil adjacent to said upper evaporator, a control valve in said by-pass line, said control valve having an open position to allow hot refrigerant gas to ow from the compressor to the defrost coil and having a closed position to allow refrigerant to flow through the condenser, a defrost restrictor positioned between said defrost coil and the top coil of said tank evaporator for expanding said refrigerant vbefore said refrigerant enters said tank evaporator, said refrigerant being directed during the refrigeration cycle to the upper evaporator and the tank evaporator for cooling same, and during the defrost cycle relatively hot refrigerant is directed into said by-pass line to said defrost coil to defrost said upper evaporator 'and is then directed through said defrost restrictor and into the tank evaporator to produce a cooling effect and thence through the accumulator and back to the compressor.

2. A refrigeration system including a compressor, a condenser, and a refrigeratio-n restriction operatively connected for circulating refrigerant, an upper evaporator and a tank evaporator each having several coils for receiving refrigerant, the coils of said tank evaporator arranged one above the other along the wall of .a tank or food compartment, a by-pass line extending from said compressor to a defrost coil adjacent to said upper evaporator, a control valve in said by-pass line said control valve having an open position to allow hot refrigerant gasto iiow from the compressor to the defrost coil and having a closed position to allow refrigerant to flow through the condenser, a defrost restrictor positioned between said defrost coil .and said tank evaporator for expanding said refrigerant, vsaid tank evaporator having" a shunt conduit between a central coil thereof and said compressor, Ia valve in said shunt conduit movable to an open position to allow refrigerant to by-pass at least one of the coils of said tank evaporator and movable to a closed position to allow refrigerant to flow through the entire tank evaporator, said refrigerant being directed during the refrigeration cycle to the upper evaporator and all of the coils of the tank evaporator for cooling same, and during the defrost cycle relatively hot refrigerant is directed into said by-pass line to said defrost coil to defrost said upper evaporator and is then directed through said defrost restrictor and into the tank evaporator to produce a cooling effect and thence through the shunt conduit and back to the compressor.

3. A refrigeration system including a compressor, a condenser, and a refrigeration restriction operatively connected for circulating refrigerant, an upper evaporator and a tank evaporator each having several coils for receiving refrigerant, the coils of said tank evaporator ar-l ranged one abovethe other along the wall of a tank or food compartment, an accumulator mounted between said tank evaporator and said compressor, a by-pass line extending from said compressor to a defrost coil adjacent to said upper evaporator, a control valve in said by-pass line, said control valve having an open position to allow hot refrigerant gas to flow from the compressor to the defrost coil and having a closed position to allow refrigerant to ow through the condenser, a defrost restrictor positioned between said defrost coil and said tank evaporator for expanding said refrigerant before said refrigerant enters said tank evaporator, said tank evaporator having a shunt conduit between an intermediate coil thereof and -said accumulator, a valve in said shunt conduit movable to an open position to allow refrigerant to by-pass at least one of the coils of said tank evaporator and movable to a closed position to allow refrigerant to flow through the entire tank evaporator, said refrigerant being directed during the refrigeration cycle to the upper evaporator and all of the coils of the tank evaporator for cooling same, and during the defrost cycle relatively hot refrigerant is directed into said by-pass line to said defrost coil to defrost said upper evaporator and is then directed through said defrost restrictor and into the tank evaporator to produce a cooling effect and thence through the shunt conduit to the accumulator and back to the compressor.

4. A refrigeration system including a compressor, a condenser, and a refrigeration restriction operatively connected for circulating refrigerant, an upper evaporator and a tank evaporator each having several coils for receiving refrigerant, the coils of said tank evaporator arranged one above the other along the wall of a tank or food compartment, an accumulator mounted between said tank evaporator and said compressor, a by-pass line extending from said compressor to a defrost coil adjacent to said upper evaporator, a control valve in said by-pass line, said control valve having an open position to allow hot refrigerant gas to ilow from the compressor to the defrost coil and having a closed position to allow refrigerant to flow through the condenser, a defrost restrictor positioned between said defrost coil and said tank evaporator for expanding said refrigerant before said refrigerant enters said tank evaporator, said tank evaporator having a shunt conduit between an intermediate coil thereof and said accumulator, a valve in said shunt conduit movable to an open position to allow refrigerant to by-pass at least one of the coils of said tank evaporator and movable to a closed position to allow refrigerant to ow through the entire tank evaporator, said refrigerant being directed during the refrigeration cycle to all of the coils of the tank evaporator and the upper evaporator for cooling same, and during the defrost cycle relatively hot refrigerant is directed into said by-pass line to said defrost coil to defrost `said upper evaporator and is then directed through said defrost restrictor and into the tank evaporator to produce ay cooling effect and thence through theshunt conduit to the accumulator and back to the compressor.

5. A refrigeration system including a compressor, a condenser, and refrigeration restriction operatively connected for circulating refrigerant, an upper evaporator and a tank evaporator each having several coils for receiving refrigerant, the coils of said tank evaporator arranged one above the other along the wall of a tank or food compartment, the coils of the upper evaporator positioned above the level of said food compartment, an accumulator mounted between said tank evaporator and said compressor, a by-pass line extending from said compressor to a defrost coil adjacent to said upper evaporator, a control valve in said by-pass line, -said control valve having an open position to allow hot refrigerant gas to ow from the compressor to the defrost coil and having a closed position to allow refrigerant to ow through the condenser, a defrost restrictor positioned between said defrost coil and the top coil of said tank evaporator for expanding said refrigerant before said refrigerant enters said tank evaporator, said evaporator having-itscoils arranged serially' so that refrigerant 'passes through each coil thereof during both the refrigeration and defrost cycles, said refrigerant being directedduring References Cited in the le of this patent UNITED STATES PATENTS 2,417,582 Bareld Mar. 18, 1947 2,451,385 Groat ---n..-- Oct. 12, 1948 20 2,688,850 White Sept. 14, 1954 2,750,758 Hoye et al. June 19, 1956 

